Roughly speaking, how are Swissgrid tariffs passed on to the lower grid levels?
Claus Reifferscheidt: We take either the previous year’s figures or planning values from our energy data to calculate Swissgrid’s cost block with us, otherwise known as upstream costs, based on the Swissgrid tariffs for 2024. By applying a specific cost reallocation method, these upstream costs are distributed proportionally to the lower grid levels: this is done according to the legal requirements, i.e. 30% of energy and 70% of power. Power is given a higher weighting because it incurs higher costs. For example, charging an electric car is cheaper at off-peak times than at midday or in the evening. We also try to shift power peaks by means of time-of-use tariffs.
Do you distinguish between tariffs for grid usage and tariffs for general or individual ancillary services?
At ewz, we don’t distinguish between general and individual ancillary services. We calculate a grid usage tariff for our end customers. For the purposes of our internal grid cost accounting, on the other hand, we look at general ancillary services on their own. However, there are some distribution system operators who charge their customers separately for ancillary services. We are currently considering the possibility of reporting general ancillary services in an isolated manner in the future for reasons of transparency, although the implementation date is still open.
How are general ancillary services and the grid surcharge passed on by the distribution system operators?
The costs for general ancillary services and the grid surcharge are passed on to us monthly on account by Swissgrid and Pronovo. At the end of September, we report the effective consumption of our end customers for the previous year to Swissgrid and then receive a final invoice. It is important to bear in mind that the purchase of ancillary services on the international power markets has increased very sharply for Swissgrid. For example, the tariff for general ancillary services has risen from 0.16 cents per kilowatt hour in 2022 to the current rate of 0.46 cents.
«It is important to bear in mind that the purchase of ancillary services on the international power markets has increased very sharply for Swissgrid.»Claus Reifferscheidt
Do you receive many comprehension questions about the nature and purpose of Swissgrid tariffs?
Actually, no, we don’t. Our customers mostly believe that we are responsible for tariff adjustments, even if we mention the major influence of Swissgrid tariffs on our tariffs when communicating with them. Many people are not aware of this. In our media release, we refer directly to the corresponding Swissgrid website to ensure clarity for customers. Our experience shows that media reports generally do the same.
It is estimated that the costs for Swissgrid’s transmission system account for an average of 8% of the total electricity price paid by end consumers throughout Switzerland. What is the approximate share of the costs for the distribution system?
According to our calculation for the ewz grid usage tariffs, the costs for the transmission system amount to around 15%. After cost reallocation, a cost centre invoice is drawn up. Then we determine which amount per grid level should be allocated to the individual tariffs for our customers. The last step is to calculate the individual components for each of our tariffs. This concludes the calculation of the ewz charges for use of the grid. General AS, energy, municipal charges and the grid surcharge are then added to the basic grid usage tariff. The financial impact on high-voltage or medium-voltage customers is greater than on low-voltage or domestic customers due to the volume of energy involved.
What is the situation as far as passing on costs for active power losses is concerned?
The Swissgrid tariff for active power losses is based on the volume of energy we purchase from the transmission system. Like the other tariff elements, this is included in the upstream costs. Our active power losses at the lower grid levels, which arise from the transport and transformation of electricity, are managed as a separate item in our grid cost accounting.
What role do distribution system operators play in setting and passing on reactive energy tariffs?
The costs for reactive energy can’t be passed on one-to-one. They are included in our grid cost calculation. Thanks to our power plants in Central Graubünden, we can contribute to the stability of the transmission system, and we are compensated accordingly. In the city of Zurich, on the other hand, we have to compensate for reactive energy ourselves so that we minimise the load on the Swissgrid grid. The tariff we charge our end customers for reactive energy has been stable for years.
Last but not least: are the distribution system operators also involved in the collection of duties and contributions to local authorities?
Absolutely! Since the duties and contributions are usually levied per kWh, it makes sense if the electricity companies are generally in charge of levying them, in a similar way to the grid surcharge. As part of the city of Zurich’s climate and energy policy goals, such as net zero, we support our customers financially with subsidies for electricity or heat from renewable sources thanks to energy advice or energy efficiency measures. In the city of Zurich, this also covers public lighting and clocks.